[flang-commits] [clang-tools-extra] [llvm] [compiler-rt] [flang] [clang] [clang] Add support for new loop attribute [[clang::code_align()]] (PR #70762)

[Erich Keane via flang-commits]

================
@@ -322,6 +322,81 @@ static Attr *handleUnlikely(Sema &S, Stmt *St, const ParsedAttr &A,
   return ::new (S.Context) UnlikelyAttr(S.Context, A);
 }
 
+CodeAlignAttr *Sema::BuildCodeAlignAttr(const AttributeCommonInfo &CI,
+                                        Expr *E) {
+  if (!E->isValueDependent()) {
+    llvm::APSInt ArgVal;
+    ExprResult Res = VerifyIntegerConstantExpression(E, &ArgVal);
+    if (Res.isInvalid())
+      return nullptr;
+    E = Res.get();
+
+    // This attribute requires an integer argument which is a constant power of
+    // two between 1 and 4096 inclusive.
+    if (ArgVal < CodeAlignAttr::MinimumAlignment ||
+        ArgVal > CodeAlignAttr::MaximumAlignment || !ArgVal.isPowerOf2()) {
+      if (std::optional<int64_t> Value = ArgVal.trySExtValue())
+        Diag(CI.getLoc(), diag::err_attribute_power_of_two_in_range)
+            << CI << CodeAlignAttr::MinimumAlignment
+            << CodeAlignAttr::MaximumAlignment << Value.value();
+      else
+        Diag(CI.getLoc(), diag::err_attribute_power_of_two_in_range)
+            << CI << CodeAlignAttr::MinimumAlignment
+            << CodeAlignAttr::MaximumAlignment << E;
+      return nullptr;
+    }
+  }
+  return new (Context) CodeAlignAttr(Context, CI, E);
+}
+
+static Attr *handleCodeAlignAttr(Sema &S, Stmt *St, const ParsedAttr &A) {
+
+  Expr *E = A.getArgAsExpr(0);
+  return S.BuildCodeAlignAttr(A, E);
+}
+
+// Diagnose non-identical duplicates as a 'conflicting' loop attr
+// and suppress duplicate errors in cases where the two match for
+// [[clang::code_align()]] attribute.
+static void
+CheckForDuplicateCodeAlignAttrs(Sema &S,
+                                const SmallVectorImpl<const Attr *> &Attrs) {
+  auto FindFunc = [](const Attr *A) { return isa<const CodeAlignAttr>(A); };
+  const auto *FirstItr = std::find_if(Attrs.begin(), Attrs.end(), FindFunc);
+
+  if (FirstItr == Attrs.end()) // no attributes found
+    return;
+
+  const auto *LastFoundItr = FirstItr;
+  std::optional<llvm::APSInt> FirstValue;
+
+  const auto *CAFA =
+      dyn_cast<ConstantExpr>(cast<CodeAlignAttr>(*FirstItr)->getAlignment());
+  // Return early if first alignment expression is dependent (since we don't
+  // know what the effective size will be), and skip the loop entirely.
+  if (!CAFA)
+    return;
+
+  while (Attrs.end() != (LastFoundItr = std::find_if(LastFoundItr + 1,
+                                                     Attrs.end(), FindFunc))) {
+    const auto *CASA =
+	dyn_cast<ConstantExpr>(cast<CodeAlignAttr>(*LastFoundItr)->getAlignment());
+    // If the value is dependent, we can not test anything.
+    if (!CASA)
+      return;
+    // Test the attribute values.
+    llvm::APSInt SecondValue = CASA->getResultAsAPSInt();
+    FirstValue = CAFA->getResultAsAPSInt();
----------------
erichkeane wrote:

```suggestion
    if (!FirstValue) FirstValue = CAFA->getResultAsAPSInt();
```

It is an optional afterall...

https://github.com/llvm/llvm-project/pull/70762